This annual was formerly an arable weed of chalk and limestone soils, but it is now a rare bird-seed casual. Lowland.
B. rotundifolium was frequent in the mid 19th century but, with seed screening, became rare by the 20th century, and has been extinct in arable habitats since the 1960s. Germination of its seed is affected by late frosts, and its persistence depended on repeated re-introductions, often with clover seed, from S.W. Europe. It is often confused with B. subovatum, and some erroneous records may be mapped. Most of the East Anglian sites are deliberate introductions.
B. rotundifolium may originate in S.W. Asia; it is widespread as an archaeophyte in C. & S. Europe and has been introduced to many other areas worldwide.
Light (Ellenberg): 8
Moisture (Ellenberg): 3
Reaction (Ellenberg): 9
Nitrogen (Ellenberg): 4
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 3.8
July Mean Temperature (Celsius): 16
Annual Precipitation (mm): 753
Count of 10km squares in Great Britain: 287
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 1
Atlas Change Index: -4.58
PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.